The invention relates to modifiers for use with window envelopes for the purpose of maintaining a preaddressed document within such an envelope in a position where the address will show at all times through the customary transparent window portion of the envelope.
Window envelopes can be obtained economically is standard sizes. The documents to be enclosed in such window envelopes may not always be of essentially the same dimensions as the inside of such envelopes, since such documents may be standard forms originally produced most economically in other standard sizes. Such documents, for example, when prepared for mailing in either folded or unfolded form, may be shorter than the inside length of such an envelope or narrower than the vertical height of the inside of the envelope, or both. If there is too much difference in the relative dimensions, the inserted document may slide out of position during mailing and transportation, so that the receipient's address is no longer in proper alignment with the usual transparent window of such an envelope. While envelopes might be manufactured on a custom basis to fit any particular document size to be mailed, such custom manufacturing may be proportionately too costly for use in a situation where a limited number of existing documents are to be mailed and where such documents do not fit rather closely within the dimensions of a standard economical window envelope.